Servo disc-reading is an important function with extensive applications. Specifically, it can be applied in disc navigators, household disc players, and disc players in computers.
Generally, a servo reading module comprises a servo control module, a pick-up head and a disc mechanism. The pick-up head is movably assembled along sliding rails of the mechanism while the servo reading module is operating to read information at different positions of the disc under control of the servo control module. During the developing process, the developer may set up a group of forces for controlling the motion of the pick-up head based on coordination of the pick-up head and the mechanism, and burn the group of forces into the servo control module to perform the disc reading function.
During fabrication, process differences might result in different spacing between the sliding rails along portions or an entire length of the sliding rails, which can affect the velocity of the pick-up head moving along the sliding rails. Said differently, the different spacing between the sliding rails can cause different regions of tightness or binding, which could lead to different pick-up head speeds when the pick-up head moves along the sliding rails under a same force. Furthermore, the difference in spacing between the sliding rails can vary from one disc reading system to another. In practical applications, however, with respect to mechanisms of the same type, mechanisms produced by different manufacturers may have different tightness, and even the same mechanism manufacturer may also produce mechanisms with different tightness due to product-line management issues.